July 25, 2012Volume 7 - Issue 30

DynaMed Weekly Update

For the week ending July 20, 2012

Last week 489 articles were evaluated via DynaMed's Systematic Literature Surveillance and 247 were added to DynaMed content.   


Based on the editors' criteria of selecting "articles most likely to change clinical practice," one article of significant interest was selected for the DynaMed Weekly Update.

Feature Article

Preexposure Prophylaxis with Tenofovir Reduces Risk of HIV Transmission in Serodiscordant Heterosexual Couples


As reported in a previous DynaMed Weekly Update (Volume 5, issue 48), preexposure prophylaxis with combination emtricitabine/tenofovir (Truvada) has been shown to reduce the risk of HIV transmission in men who have sex with men (N Engl J Med 2010 Dec 30;363(27):2587). The PrEP trial recently evaluated the prophylactic efficacy of this combination drug and of tenofovir alone in Uganda and Kenya among heterosexual couples in which 1 partner had HIV-1 infection.


A total of 4,758 couples serodiscordant for HIV-1 infection were randomized to 1 of 3 daily oral regimens for the partner without HIV-1 infection: tenofovir 300 mg/day, combination of tenofovir 300 mg plus emtricitabine 200 mg, or placebo. The partner without infection (male partner in 62% of couples) had monthly HIV-1 testing for up to 36 months. All patients received risk reduction counseling, condoms, and HIV-1 prevention information. Various outreach interventions were used to maintain adherence based on local plans and resources. After randomization, 11 couples were excluded for ineligibility.


HIV-1 seroconversion occurred in 22 partners with tenofovir alone, 16 partners with emtricitabine/tenofovir, and 58 partners with placebo. The seroconversion rates per 100 person-years were 0.84 for tenofovir alone (p < 0.001 vs. placebo, NNT 73 for 1 year), 0.61 for emtricitabine/tenofovir (p < 0.001 vs. placebo, NNT 63 for 1 year) and 2.22 for placebo (level 1 [likely reliable] evidence). The seroconversion rates between the 2 active treatments were not significantly different, and both tenofovir-based regimens were associated with significant reductions in seroconversion compared to placebo in subgroup analyses of male and female partners. If the seronegative partner was female, the risk reduction was 71% with tenofovir and 66% with combination therapy. For male seronegative participants the risk reduction was 63% with tenofovir and 84% with combination therapy. There were no significant differences in adverse events across groups (N Engl J Med 2012 Jul 11 early online).


Truvada has recently been approved by the FDA for preexposure prophylaxis in persons at high risk of HIV infection and who engage in sexual activity with partners with HIV infection (FDA Press Release 2012 Jul 16).


For more information, see the HIV infection topic in DynaMed.

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About DynaMed Weekly Update

Prepared by the clinician members of the DynaMed Editorial Team, DynaMed Weekly Update is a compilation of one to five articles selected from DynaMed's Systematic Literature Surveillance as articles most likely to change clinical practice.

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CME Information


0.25 AMA PRA Category I Credit(s)™
Family Physicians: 0.25 Prescribed credits
Nurse Practitioners: 0.25 Contact hours
Release Date: July 25, 2012
Expiration Date: July 25, 2013
Estimated Completion Time:
15 minutes
There is no fee for this activity.

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In order to receive your certificate of participation, you should read the information about this activity, including the disclosure statements, review the entire activity, take the post-test, and complete the evaluation form. You may then follow the directions to print your certificate of participation. To begin, click the CME icon at the end of the article.

Program Overview

Learning Objectives

Upon successful completion of this educational program, the reader should be able to:
1. Discuss the significance of this article as it relates to your clinical practice.
2. Be able to apply this knowledge to your patient's diagnosis, treatment and management.
Faculty Information
Alan Ehrlich, MD - Assistant Clinical Professor in Family Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA; Deputy Editor, DynaMed, Ipswich, Massachusetts, USA

Michael Fleming, MD, FAAFP - Assistant Clinical Professor of Family Medicine and Comprehensive Care, LSU Health Science Center School of Medicine, Shreveport, Louisiana, USA; Assistant Clinical Professor of Family Medicine, Department of Family and Community Medicine, Tulane University Medical School, New Orleans, Louisiana, USA; Chief Medical Officer, Amedisys, Inc. & Antidote Education Company

Dr. Ehrlich, Dr. Fleming, DynaMed Editorial Team members, and the staff of Antidote Education Company have disclosed that they have no relevant financial relationships or conflicts of interest with commercial interests related directly or indirectly to this educational activity.
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AAFPEnduring Material activity, DynaMed Weekly Update, has been reviewed and is acceptable for up to 13 Prescribed credits by the American Academy of Family Physicians. AAFP certification begins March 7, 2012. Term of approval is for one year from this date with the option of yearly renewal. Each Weekly Update is worth .25 Prescribed credits. Physicians should claim only the credit commensurate with the extent of their participation in the activity.


AANP: This program is approved for 0.25 contact hour of continuing education by the American Academy of Nurse Practitioners.    

Program ID:1102072U. 

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